Gelation and flocculation of casein micelle/carrageenan mixtures

The specific attractive interaction between carrageenan and casein micelles is widely exploited in the daily industry to tailor the texture of dairy desserts. However, in industrial practice it has been observed that the addition of carrageenan can cause casein micelles to sediment rapidly when the mixture is above the gelation temperature. To better understand this undesirable phenomenon, carrageenan/skim milk mixtures have been observed over a wide range of compositions at 65 and 25 degrees C. Interactions occurred for iota, kappa and lambda carrageenan at both temperatures. At 65 degrees C sedimentation was observed when the carrageenan concentration was above 0.2%. At 25 degrees C either phase separation or gelation could occur Depletion flocculation is suggested as a partial explanation for these observations The effects of casein micelles on the viscoelastic properties of iota carrageenan have been measured in the absence of flocculation. Their presence decreases carrageenan's gelation concentration and increases both the gelation temperature and the elastic modulus.